Construction of Co-Derived Heterojunction Affected by Multi-Walled Carbon Nanotubes/Graphene Oxide toward Superior Microwave Absorption Performance

Co/MWCNTs/GO ternary composites were successfully constructed through a multidimensional synergistic design strategy. Multi-walled carbon nanotubes (MWCNTs) and graphene oxide (GO) were co-assembled to form a stable conductive network, and Co was uniformly dispersed on the network. The influence of thermal oxidation time (0−180 min) on the phase evolution and electromagnetic parameters of the Co/MWCNTs/GO composite was investigated. Notably, under an oxidation time of 60 min, the composite exhibits optimal performance at a 10 wt % filler loading, with a minimum reflection loss (RLmin) of −49.7 dB at 12.08 GHz and an effective absorption bandwidth (EAB) of 7.28 GHz at a thickness of 2.2 mm. The three-dimensional network facilitates rapid electron transport and polarization relaxation, resulting in impedance matching and pronounced attenuation capability in the low-frequency range. The gradually formed multiphase interface significantly enhances interfacial polarization. The electronic transport pathways provided by the MWCNTs/GO conductive network promote dielectric loss behavior, while the generation of cobalt oxide further introduces a magnetic loss mechanism. This construction of a dielectric-magnetic synergistic absorption system (Co-derived heterojunction affected by MWCNTs/GO) provides crucial guidance for designing lightweight, highly efficient MWA materials.